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Clinical Anatomy (New York, N.Y.) Nov 2014The optic chiasm is formed when the optic nerves come together in order to allow for the crossing of fibers from the nasal retina to the optic tract on the other side.... (Review)
Review
The optic chiasm is formed when the optic nerves come together in order to allow for the crossing of fibers from the nasal retina to the optic tract on the other side. This enables vision from one side of both the eyes to be appreciated by the occipital cortex of the opposite side. This review makes note of the embryology, anatomy and vascular supply of the optic chiasm, then discusses the clinical syndromes associated with chiasmal disease, and the diseases which commonly influence its function.
Topics: Adenoma; Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis; Arachnoid Cysts; Central Nervous System Cysts; Craniopharyngioma; Glioma; Humans; Optic Chiasm; Optic Nerve Diseases; Optic Nerve Neoplasms; Pituitary Neoplasms; Sarcoidosis; Tuberculosis; Visual Fields; Visual Pathways
PubMed: 24824063
DOI: 10.1002/ca.22385 -
Handbook of Clinical Neurology 2021Perimetry is the quantitation of the visual field. This is done with a perimeter and usually involves measuring visual thresholds to a range of light stimuli. It is used... (Review)
Review
Perimetry is the quantitation of the visual field. This is done with a perimeter and usually involves measuring visual thresholds to a range of light stimuli. It is used clinically to map patterns of visual loss due to damage to the sensory visual system. This chapter discusses the types of perimetric testing and the psychophysics of perimetry. This is followed by the interpretation of perimetric results, the relevant visual system anatomy, and patterns of loss helpful for neurologic localization. Lastly, the difficult issue of deciding whether the visual field has changed is reviewed. Patterns of visual loss are the key to anatomic diagnosis. Strictly monocular defects map to the prechiasmal sensory visual system. Bitemporal hemianopia is the signature of damage to the optic chiasm. Incongruous homonymous hemianopia points to an optic tract lesion. The closer a lesion gets to the occipital cortex, the more congruous or similar are the patterns of homonymous hemianopia. Understanding these patterns, the basics of perimetry and other rules of localization will add an important dimension to the neurologist's localization arsenal.
Topics: Hemianopsia; Humans; Optic Chiasm; Vision Disorders; Visual Field Tests; Visual Fields
PubMed: 33832687
DOI: 10.1016/B978-0-12-821377-3.00003-9 -
Journal of Medical Ultrasound 2023This article reviews the literature on different methods of prenatal ultrasound visualization of the optic chiasm (OC) and its applications. Prenatal imaging of the OC... (Review)
Review
This article reviews the literature on different methods of prenatal ultrasound visualization of the optic chiasm (OC) and its applications. Prenatal imaging of the OC is feasible from 19 to 37 weeks of gestation. Evaluation of the OC has been shown crucial in differentiating isolated agenesis of the septum pellucidum from septo-optic dysplasia. Multiple methods can be applied for imaging of the OC, including three-dimensional and two-dimensional ultrasounds in different views, as well as color Doppler. According to the literature, both transabdominal and transvaginal routes produce equally acceptable images. OC visualization might be challenging but can be achieved by developing a standard scanning protocol and raising awareness.
PubMed: 38025017
DOI: 10.4103/jmu.jmu_69_23 -
Neurologia Medico-chirurgica Jan 2018Optic pathway/hypothalamic gliomas (OP/HGs) are rare astrocytic tumors that appear more commonly among young children and often are unresectable. They comprise... (Review)
Review
Optic pathway/hypothalamic gliomas (OP/HGs) are rare astrocytic tumors that appear more commonly among young children and often are unresectable. They comprise approximately 2% of all central nervous system tumors and account for 3-5% of pediatric intracranial tumors. Initial manifestations are often visual disturbances, endocrinopathies and hypothalamic dysfunction such as the diencephalic syndrome, and sometimes hydrocephalus due to cerebrospinal fluid (CSF) outflow obstruction. In many cases, the tumors are diagnosed late in the clinical course because they silently enlarge. These tumors consist mostly of histologically benign, World Health Organization (WHO) grade I tumors represented by pilocytic astrocytomas (PA), the rest being pilomyxoid astrocytomas (PXA) - WHO grade II tumors. In young pediatric patients, however, can be seen PXA that show aggressive clinical course such as CSF dissemination. Our small series of 14 non-Neurofibromatosis type 1 (NF-1) OP/HGs PA patients underwent extended resection without any adjuvant treatments. The median age at initial treatment was 11.5 ± 6.90 years (range, 1-25 years) and median follow up 85.5 ± 25.0 months. Surgical resection for OP/HGs results in acceptable middle-term survival, tumor control and functional outcome equivalent to chemotherapy. There is, however, no longer doubt that chemotherapy with or without biopsy and as-needed debulking surgery remains the golden standard in management of OP/H. Clinical conditions and treatment plans for OP/HGs vary depending on their structure of origin.
Topics: Adolescent; Brain Neoplasms; Child; Child, Preschool; Female; Glioma; Humans; Hypothalamus; Infant; Male; Optic Chiasm; Optic Tract; Young Adult
PubMed: 29118304
DOI: 10.2176/nmc.ra.2017-0081 -
Magnetic Resonance Imaging Jun 2021The optic nerve is known to be one of the largest nerve bundles in the human central nervous system. There have been many studies of optic nerve imaging and... (Review)
Review
The optic nerve is known to be one of the largest nerve bundles in the human central nervous system. There have been many studies of optic nerve imaging and post-processing that have provided insights into pathophysiology of optic neuritis related to multiple sclerosis and neuromyelitis optica spectrum disorder, glaucoma, and Leber's hereditary optic neuropathy. There are many challenges in optic nerve imaging, due to the morphology of the nerve through its course to the optic chiasm, its mobility due to eye movements and the high signal from cerebrospinal fluid and orbital fat surrounding the optic nerve. Recently, many advanced and fast imaging sequences have been used with post-processing techniques in attempts to produce higher resolution images of the optic nerve for evaluating various diseases. Magnetic resonance imaging (MRI) is one of the most common imaging methodologies for the optic nerve. This review paper will focus on recent MRI advances in optic nerve imaging and explain several post-processing techniques being used for analysis of optic nerve images. Finally, some challenges and potential for future optic nerve studies will be discussed.
Topics: Humans; Magnetic Resonance Imaging; Multiple Sclerosis; Optic Chiasm; Optic Nerve; Optic Neuritis
PubMed: 33753137
DOI: 10.1016/j.mri.2021.03.014 -
Current Opinion in Endocrinology,... Aug 2016Patients with pituitary diseases have decreased quality of life. Sleep disorders are prevalent among patients with pituitary diseases and contribute to decreased quality... (Review)
Review
PURPOSE OF REVIEW
Patients with pituitary diseases have decreased quality of life. Sleep disorders are prevalent among patients with pituitary diseases and contribute to decreased quality of life.
RECENT FINDINGS
Patients previously treated for compression of the optic chiasm by surgery, and in some cases postoperative radiotherapy, suffer from sleep disorders. These are characterized by decreased sleep quality, delayed onset of sleep, and daytime sleepiness. Circumstantial evidence suggests that this may be caused by hypothalamic dysfunction. A challenging speculation is that previous compression of the optic chiasm compromised the function of the retinohypothalamic tract. Through this tract the eyes convey information on day-night cycles to the hypothalamic nuclei. Patients with acromegaly, even despite biochemical control, suffer frequently from obstructive sleep apnea. Patients with Cushing's disease suffer from fragmented sleep, sleep apnea, and snoring. Prolactinomas do not seem to affect sleep characteristics. The association between appropriately substituted pituitary insufficiency and sleep disorders is less clear. The effects of recombinant human growth hormone on sleep characteristics in adults are inconsistent.
SUMMARY
Pituitary disorders are associated with different sleep disorders. Different studies point to irreversible changes in sleep-wake rhythmicity in patients treated previously for pituitary tumors with chiasm compression. VIDEO ABSTRACT.
Topics: Humans; Optic Chiasm; Pituitary Diseases; Sleep Wake Disorders
PubMed: 27254266
DOI: 10.1097/MED.0000000000000265 -
Child's Nervous System : ChNS :... Nov 2017The optic chiasm is an essential structure located at the skull base that stirred over time the curiosity of anatomists, who became more and more interested in its... (Review)
Review
PURPOSE
The optic chiasm is an essential structure located at the skull base that stirred over time the curiosity of anatomists, who became more and more interested in its structure and function. Through centuries, the optic chiasm was viewed as a vessel crossing, a way of transporting tears secreted by the brain to the eye, integrating images, or responsible for coordinated eye movements. The paper aims to overview the history of understanding the optic chiasm from the beginnings of antiquity to the twentieth century.
METHODS
We reviewed the literature and studied all the historical sources on optic chiasm and eyes in the works of ancient, medieval, Renaissance authors, and the seventeenth to nineteenth century works.
RESULTS
The optic chiasm is a structure that fascinated ancient anatomists and made them develop various theories on its function. In terms of function, the optic chiasm had a history based more on speculation, the seventeenth century bringing its first understanding and reaching the peak in the nineteenth century with the understanding of the anatomical structure of the chiasm and its role in the visual process.
CONCLUSION
The history of the optic chiasm is a fascinating time travel displaying the conceptual transformations that have been made in anatomy and medicine by our forerunners.
Topics: History, 15th Century; History, 16th Century; History, 17th Century; History, 18th Century; History, 19th Century; History, 20th Century; History, Ancient; History, Medieval; Humans; Ophthalmology; Optic Chiasm
PubMed: 28808784
DOI: 10.1007/s00381-017-3564-1 -
The New England Journal of Medicine Feb 2023
Topics: Humans; Arachnoiditis; Optic Chiasm; Tuberculosis, Meningeal
PubMed: 36779645
DOI: 10.1056/NEJMicm2205437 -
Neuroimaging Clinics of North America Aug 2015Optic neuropathy involves loss of visual acuity, color vision, and visual field defect with a swollen, pale, anomalous, or normal optic disc seen on fundoscopy. Chiasmal... (Review)
Review
Optic neuropathy involves loss of visual acuity, color vision, and visual field defect with a swollen, pale, anomalous, or normal optic disc seen on fundoscopy. Chiasmal disorders classically present with gradual onset of vision loss, bitemporal hemianopsia, and occasionally, endocrinopathy if the pituitary gland and/or hypothalamus are the causes or are involved. Advance in neuroimaging, especially magnetic resonance (MR) imaging, can reveal pathologic conditions previously detected only clinically. Some entities have imaging characteristics, leading to appropriate treatment without requiring tissue biopsies. Imaging also provides disease surveillance and posttreatment assessment, with computed tomography and MR imaging being complementary to each other.
Topics: Humans; Image Enhancement; Magnetic Resonance Imaging; Neuroimaging; Optic Chiasm; Optic Nerve Diseases; Syndrome; Tomography, X-Ray Computed; Vision Disorders
PubMed: 26208416
DOI: 10.1016/j.nic.2015.05.004 -
Journal of Clinical Neuroscience :... Jul 2015We report a 55-year-old woman with optic nerve Aspergillosis. Aspergillus is an ubiquitous airborne saprophytic fungus. Inhaled Aspergillus conidia are normally...
We report a 55-year-old woman with optic nerve Aspergillosis. Aspergillus is an ubiquitous airborne saprophytic fungus. Inhaled Aspergillus conidia are normally eliminated in the immunocompetent host by innate immune mechanisms; however, in immunosuppressed patients, they can cause disease. The woman had a past medical history of hypertension and migraines. She presented 1 year prior to death with a new onset headache behind the left eye and later developed blurred vision and scotoma. A left temporal artery biopsy was negative for giant cell arteritis. One month prior to the current admission, she had an MRI showing optic nerve thickening with no other findings. Because of the visual loss and a positive antinuclear antibody test, she was given a trial of high dose steroids and while it significantly improved her headache, her vision did not improve. At autopsy, the left optic nerve at the level of the cavernous sinus and extending into the optic chiasm was enlarged in diameter and there was a 1.3 cm firm nodule surrounding the left optic nerve. Histologically, an abscess surrounded and involved the left optic nerve. Acute angle branching, angioinvasive fungal hyphae were identified on Grocott's methenamine silver stained sections, consistent with Aspergillus spp. No gross or microscopic evidence of systemic vasculitis or infection was identified in the body. The literature on optic nerve Aspergillosis is reviewed.
Topics: Abscess; Aspergillosis; Autopsy; Fatal Outcome; Female; Headache; Humans; Middle Aged; Optic Chiasm; Optic Nerve; Optic Nerve Diseases; Scotoma; Steroids; Vision Disorders
PubMed: 25861888
DOI: 10.1016/j.jocn.2015.01.012